1. (1) K. Atallash, J. Rens, S. Mezani, and D. Howe: “A novel “pseudo” direct-drive brushless permanent magnet machine”, IEEE Trans. on Magnetics, Vol. 44, No. 11, pp. 4349-4352 (2008)
2. (2) I. A. Smadi, H. Omori, and Y. Fujimoto: “Development, analysis and experimental realization of a direct-drive helical motor”, IEEE Trans. on Industrial Electronics, Vol. 59, No. 5, pp. 2208-2216 (2012)
3. (3) A. A. Schäffer, S. Haddadin, C. Ott, A. Stemmer, T. Wimböck, and G. Hirzinger: “The DLR lightweight robot: design and control concepts for robots in human environments”, Industrial Robot, Vol. 34, No. 5, pp. 376-385 (2007)
4. (4) T. Kawakami, K. Ayusawa, H. Kaminaga, and Y. Nakamura: “High-fidelity joint drive system by torque feedback control using high precision linear encoder”, Proc. IEEE Int. Conf. on Robotics and Automation, pp. 3904-2909 (2010)
5. (5) Y. Yokokura, K. Ohishi, K. Saito, and A. Shimamoto: “Torque control of geared motor with load-side torque sensor using acceleration observer”, Proc. IEEJ Int. Workshop on Sensing Actuation and Motion Control, IS6-6 (2015)